AP BIOLOGY EXAM FREE RESPONSE
QUESTIONS AND ANSWERS
Water has a high specific heat.
Explain what high specific heat means and state one way it favorably affects living
things.
Explain the chemical property of water responsible for thie characteristic - Correct
Answers -Specific heat is the amount of heat required to raise the temperature of 1
gram of a substance 1 degree C. Because water has a high specific heat, oceans resist
changes in temperature and provide a stable environmental temperature for organisms
to live in. Furthermore, oceans moderate the climate of nearby land. Water has a high
specific heat because of the strong hydrogen bonding between water molecules.
Water is known as a universal solvent. Explain why so many substances are soluable in
water. - Correct Answers -Since water is a polar substance, all polar and ionic
substances will dissolve in it. The only substances that will not dissolve in water are
nonpolar substances, such as oils and fats.
The unique properties of water make life on Earth possible. Select four characteristics of
water and:
a. identify one characteristic of water, and explain how the structure of water relates to
this property
b. describe one example of how this characteristic affects living organisms - Correct
Answers -a. Water is a highly polar molecule with strong hydrogen bonding between
adjacent water molecules. Because there are such strong attractions between
molecules, water has certain properties that make life on Earth possible. These
properties are high cohesion tension, high specific heat, high heat of vaporization, and
the fact that water is an excellent solvent. Another property of water is that when it is
frozen, it is less dense than water. The reason for this is that the bonding between the
water molecules in ice holds the molecules rigidly and farther apart than in liquid water.
Since the water molecules are farther apart in ice than in water, ice is less dense than
water
b. Because ice is less dense than water, it floats. This has important consequences for
living things. In a deep body of water, such as a lake, floating ice insulates the liquid
water below it, allowing life to exist beneath the frozen surface during cold seasons. The
fact that ice covers the surface of water in the cold months and melts in the spring
results in a stratification of the lake in winter and considerable mixing in the spring when
the ice melts. In the spring, the ice melts, becomes denser water, and sinks to the
bottom of the lake, causing water to circulate throughout the lake. Oxygen from the
, surface is returned to the depths, and nutrients released by the activities of bottom
dwelling bacteria during the winter are carried to the upper layers of the lake. This
cycling of the nutrients in the lake is known as the spring overturn and is a necessary
part of the life cycle of a lake.
Compare and constrast two human cells: one a liver cell and one a fat cell - Correct
Answers -Both cells would contain all of the same organelles, including a nucleus,
mitochondria, vacuoles, nucleoli, ribosomes, and ER. However, the liver cell would have
a much larger amount of smooth ER for detoxifying the body, while the fat cell would
have one or more large vacuoles for storing fat and very little smooth ER.
You prepare a slide of living elodea leaf and look at the cells under 40x magnification.
You see many rectangular shaped cells filled with green chloroplasts. While you are
observing the tissue, you carefully place three drops of 4% salt solution next to the right
side of the cover slip and draw the slution acrss the slide by holding a piece of paper
towel on the left edge of the cover slip. You notice that suddenly the chlroplasts have
clustered into the middle of every cell and are surrounded by a membrane. The cell
walls remain unchanged. Explain what has occurred and the mechanism behind it. -
Correct Answers -Because the salt water solution is hypertonic to the elodea cells,
water from inside the cells diffuses rapidly out of the cells. The water moves from the
region of a high concentration of water to a low concentration of water. The chloroplasts
are clustered in the middle of the cells, enclosed within the cell membrane, because all
the water left the cytoplasm
compare and contrast the characteristics of prokaryotic and eukaryotic cells - Correct
Answers -being the ancestor of all cells, prokaryotic cells have certain things in common
with eukaryotic cells. They both have DNA, a cell wall in plant cells, and cytoplasm.
Prokaryotic cells, like eukaryotic cells, carry out a wide range of metabolic proceses
including glycolosis, photosynthesis, and respiration; but prokaryotes carry them out in a
far simpler fashion. Prokaryotes are generally small, while eukaryotic cells are 10 times
larger. Prokaryotic cells have circular DNA while eukaryotes have long, linear DNA
molecules with many noncoding regions encircled by a nuclear membrane. Prokaryotes
are mainly unicellular, while eukaryotes are mostly multicellular. Prokaryotes have no
cytoskeleton and no internal membranes. Metabolism in prokaryotes can be anaerobic
or aerobic, but in eukaryotes metabolism is aerobic. Only eukaryotes have an elaborate
cytoskeletal structure and an array of internal membranes such as the Golgi, ER,
mitochondia, chloroplasts, and vacuoles.
Living cells are highly organized and regulated.
a. Describe the structure of the plasma membrane
b. Explain how the plasma membrane contributes to the regulation of the cell - Correct
Answers -a. in 1972, S.J. Singer elucidated the structure of the cell membrane, which
he called the fluid mosaic model. The plasma membrane is a selectively permeable and
dynamic, fluid structure consisting of a continuous double phospholipid layer about 5 nm
thick, with proteins dissolved throughout the bilayer. The phospholipids are amphipathic,
meaning they have polar, hydrophilic heads and nonpolar, hydrophobic tails. The polar
QUESTIONS AND ANSWERS
Water has a high specific heat.
Explain what high specific heat means and state one way it favorably affects living
things.
Explain the chemical property of water responsible for thie characteristic - Correct
Answers -Specific heat is the amount of heat required to raise the temperature of 1
gram of a substance 1 degree C. Because water has a high specific heat, oceans resist
changes in temperature and provide a stable environmental temperature for organisms
to live in. Furthermore, oceans moderate the climate of nearby land. Water has a high
specific heat because of the strong hydrogen bonding between water molecules.
Water is known as a universal solvent. Explain why so many substances are soluable in
water. - Correct Answers -Since water is a polar substance, all polar and ionic
substances will dissolve in it. The only substances that will not dissolve in water are
nonpolar substances, such as oils and fats.
The unique properties of water make life on Earth possible. Select four characteristics of
water and:
a. identify one characteristic of water, and explain how the structure of water relates to
this property
b. describe one example of how this characteristic affects living organisms - Correct
Answers -a. Water is a highly polar molecule with strong hydrogen bonding between
adjacent water molecules. Because there are such strong attractions between
molecules, water has certain properties that make life on Earth possible. These
properties are high cohesion tension, high specific heat, high heat of vaporization, and
the fact that water is an excellent solvent. Another property of water is that when it is
frozen, it is less dense than water. The reason for this is that the bonding between the
water molecules in ice holds the molecules rigidly and farther apart than in liquid water.
Since the water molecules are farther apart in ice than in water, ice is less dense than
water
b. Because ice is less dense than water, it floats. This has important consequences for
living things. In a deep body of water, such as a lake, floating ice insulates the liquid
water below it, allowing life to exist beneath the frozen surface during cold seasons. The
fact that ice covers the surface of water in the cold months and melts in the spring
results in a stratification of the lake in winter and considerable mixing in the spring when
the ice melts. In the spring, the ice melts, becomes denser water, and sinks to the
bottom of the lake, causing water to circulate throughout the lake. Oxygen from the
, surface is returned to the depths, and nutrients released by the activities of bottom
dwelling bacteria during the winter are carried to the upper layers of the lake. This
cycling of the nutrients in the lake is known as the spring overturn and is a necessary
part of the life cycle of a lake.
Compare and constrast two human cells: one a liver cell and one a fat cell - Correct
Answers -Both cells would contain all of the same organelles, including a nucleus,
mitochondria, vacuoles, nucleoli, ribosomes, and ER. However, the liver cell would have
a much larger amount of smooth ER for detoxifying the body, while the fat cell would
have one or more large vacuoles for storing fat and very little smooth ER.
You prepare a slide of living elodea leaf and look at the cells under 40x magnification.
You see many rectangular shaped cells filled with green chloroplasts. While you are
observing the tissue, you carefully place three drops of 4% salt solution next to the right
side of the cover slip and draw the slution acrss the slide by holding a piece of paper
towel on the left edge of the cover slip. You notice that suddenly the chlroplasts have
clustered into the middle of every cell and are surrounded by a membrane. The cell
walls remain unchanged. Explain what has occurred and the mechanism behind it. -
Correct Answers -Because the salt water solution is hypertonic to the elodea cells,
water from inside the cells diffuses rapidly out of the cells. The water moves from the
region of a high concentration of water to a low concentration of water. The chloroplasts
are clustered in the middle of the cells, enclosed within the cell membrane, because all
the water left the cytoplasm
compare and contrast the characteristics of prokaryotic and eukaryotic cells - Correct
Answers -being the ancestor of all cells, prokaryotic cells have certain things in common
with eukaryotic cells. They both have DNA, a cell wall in plant cells, and cytoplasm.
Prokaryotic cells, like eukaryotic cells, carry out a wide range of metabolic proceses
including glycolosis, photosynthesis, and respiration; but prokaryotes carry them out in a
far simpler fashion. Prokaryotes are generally small, while eukaryotic cells are 10 times
larger. Prokaryotic cells have circular DNA while eukaryotes have long, linear DNA
molecules with many noncoding regions encircled by a nuclear membrane. Prokaryotes
are mainly unicellular, while eukaryotes are mostly multicellular. Prokaryotes have no
cytoskeleton and no internal membranes. Metabolism in prokaryotes can be anaerobic
or aerobic, but in eukaryotes metabolism is aerobic. Only eukaryotes have an elaborate
cytoskeletal structure and an array of internal membranes such as the Golgi, ER,
mitochondia, chloroplasts, and vacuoles.
Living cells are highly organized and regulated.
a. Describe the structure of the plasma membrane
b. Explain how the plasma membrane contributes to the regulation of the cell - Correct
Answers -a. in 1972, S.J. Singer elucidated the structure of the cell membrane, which
he called the fluid mosaic model. The plasma membrane is a selectively permeable and
dynamic, fluid structure consisting of a continuous double phospholipid layer about 5 nm
thick, with proteins dissolved throughout the bilayer. The phospholipids are amphipathic,
meaning they have polar, hydrophilic heads and nonpolar, hydrophobic tails. The polar
